SN74ALVC7803 Datasheet, PDF (8/14 Pages) Texas Instruments – 512 × 18 CLOCKED FIRST-IN, FIRST-OUT MEMORY

SN74ALVC7803
512 × 18
CLOCKED FIRST-IN, FIRST-OUT MEMORY
SDAS274 – JANUARY 1995
offset values for AF/AE
The AF/AE flag has two programmable limits: the almost-empty offset value (X) and the almost-full offset value
(Y). They can be programmed after the FIFO is reset and before the first word is written to memory. If the offsets
are not programmed, the default values of X = Y = 64 are used. The AF/AE flag is high when the FIFO contains
X or less words or (512 minus Y) or more words.
Program enable (PEN) should be held high throughout the reset cycle. PEN can be brought low only when IR
is high. On the following low-to-high transition of WRTCLK, the binary value on D0 – D7 is stored as the almost
empty offset value (X) and the almost full offset value (Y). Holding PEN low for another low-to-high transition
of WRTCLK reprograms Y to the binary value on D0 – D7 at the time of the second WRTCLK low-to-high
transition. When the offsets are being programmed, writes to the FIFO memory are disabled regardless of the
state of WRTEN1 and WRTEN2. A maximum value of 255 can be programmed for either X or Y
(see Figure 4). To use the default values of X = Y = 64, PEN must be held high.
RESET
WRTCLK ³
4
PEN
D0–D7 ^{ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ}XandY
ÉÉ_{Y ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ}
IR
WRTEN1
WRTEN2
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
Figure 4. Programming X and Y Separately
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)^†
Supply voltage range, V_CC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.5 V to 4.6 V
Input voltage range, V_I (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 4.6 V
Output voltage range, V_O (see Notes 1 and 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.5 V to V_CC + 0.5 V
* Input clamp current, I_IK ( V_I < 0 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mA
" Output clamp current, I_OK ( V_O < 0 or V_O > V_CC ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mA
" Continuous output current, I_O ( V_O = 0 to V_CC ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mA
" Continuous current through V_CC or GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mA
Voltage applied to a disabled 3-state output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 V
Operating free-air temperature range, T_A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
† _{Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and}
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTES: 1. The input and output voltage ratings can be exceeded if the input and output clamp current ratings are observed.
2. This value is limited to 4.6 V maximum.
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